Dovetailing

Description

Dovetailing

There is another way of joining two pieces meeting at right angles, and it is better and stronger than any other but, on account of the work involved in the process of making the joint, is seldom used except in the best work. This method is known as dovetailing and there are three different ways of arranging the dovetails as will be shown. The first is the simple dovetail which is illustrated in Fig. 87. As will be seen, it consists in cutting tenons in the end of one piece and mortises in the end of the other piece, which are of such a shape as to form a sort of locking device, so that the pieces can be separated only by a pull in one particular direction. The use of glue makes the joint still stronger. Of course, the forming of a joint of this kind requires a large amount of time and considerable skill.

Fig. 85. Method of Binding Boards Together by Means of Strip with Slots and Screws.

A variation of the simple dovetail joint which is much used in the manufacture of drawers and in any other position where it is desirable that the joint shall be concealed from one side only, is shown in Fig. 88. This is called a lap dovetail, its peculiarity consisting in the fact that in one of the pieces the mortises are not cut the full thickness, but only partly through the wood, so as to leave a covering or lap, which prevents the joint from being seen.

A further development of the dovetail joint is shown in Fig. 89. In this case the work is so arranged that the joint can not be seen from any side of the finished product. This is accomplished by cutting the same tenons and mortises as in the case of the simple dovetail joint, but not directly on the end of the pieces. They are so cut as to project at an angle of forty-five degrees, and thus to form a combination of the mitered joint and the dovetail joint with the tenons and mortises entirely out of sight when the pieces have been put together. This joint is obviously not so strong as are the other forms of dovetail joints because the tenons are not so large.

Let us next consider the framing of the walls of a wood or frame building. In this work there are two distinct methods of procedure, known, respectively, as "braced framing" and "balloon framing," of which the first is the older and the stronger method, while the second is a modern development and claims to be more logical and at the same time more economical than the other. Balloon framing has come into use only since about the year 1850, and it is still regarded with disfavor by many architects, especially by those in the eastern states. Figs. 90 and 91 show the framing of one end of a small building by each of the two methods, the braced framing in Fig. 90 and the balloon framing in Fig. 91. Braced Frame. In a full-braced frame all the pieces should be fastened together with mortise-and-tenon joints, but this requirement is much modified in common practice, a so-called "combination" frame being used in which some pieces are mortised together and others are fastened by means of spikes only. A framework is constructed consisting in each wall of the two "corner posts" AA, Fig. 90, the "sill" B, and the "plate" C, together with a horizontal "girt" D at each story to support the floors, and a diagonal "brace" E at each corner, which, by keeping the corner square, prevents the frame from being distorted.